1. Field of the Invention
This invention relates to a conveying device for conveying a sheet and a recording apparatus for recording an image recorded upon a sheet conveyed by the conveying device.
2. Description of Related Art
Conventionally, as for a recording apparatus of this type, there is a recording apparatus such as an inkjet type printer. Among such type, there is a type using a full line type recording head having plural discharge ports arranged in a sheet-width direction, in which high speed and high grade recording is possible.
Accordingly, a commonly known conveying method is a method of arranging a conductive electrode to a conveying device for such recording apparatus, generating a static electricity by supplying electric voltage, and enabling attraction (absorption) of a conveying article such as a sheet.
FIG. 18 is a schematic structural view of a conventional conveying device and recording apparatus, and FIG. 19 is a schematic cross-sectional view of an attraction means (also illustrates electric supplying means).
An attraction means 536 is arranged to a conveyor belt 531. The attraction means 536 is comprised of an electrode plate 536a made from a conductive metal, a base layer 536c, a surface layer 536b, a targeted electric supply portion 536e, in which the surface layer 536d and the targeted electric supply portion 536e are in a flat state.
Electric voltage is supplied to the electrode plate 536a from the electric supplying brush 551 contacting with a targeted electric supply portion for generating electrostatic power. Owing to the generated electrostatic power, a constant suitable attraction strength is generated upon a conveyed article such as a sheet. Further, the electric power applied from electric supplying brush 551 is removed by an electric removal brush 539.
Nevertheless, with the conventional structure as shown in FIG. 18, when the electric supplying brush of the electric supplying means serving to supply high electric voltage makes contact with the targeted electric supply portion 536e of the conveyor belt or when the electric removal brush 539 makes contact with the targeted electric supply portion, noise would be created from the large electric potential difference.
Further, as explained above, since the electric supplying brush 551 is suddenly applied with high voltage when making contact with the electric supply portion 536e, the electric supplying brush 551 receives shock when such making contact (when supplying electricity), which raises a problem of endurance when used for a long period; further, since the electric removal brush 539 is suddenly short-circuited when making contact with the electric supply portion 536e, the electric removal brush 539 receives shock when making such contact (when removing electric power), which raises a problem of endurance when used for a long period.
Therefore, it is an object of this invention to reduce noise created when supplying electricity, to reduce shock when supplying electricity or when removing electric power, and to heighten the endurance of an electric supplying brush and an electric removal brush.
In means to achieve the foregoing object, this invention provides a sheet conveying device for attracting (absorbing) a sheet by electric power and conveying the sheet, the sheet conveying device comprising: a belt arranged with an electrode; and a plurality of electric supplying means being aligned in a sheet conveying direction for supplying electric voltage to the electrode, wherein an electric voltage value for an electric supplying means arranged at a primary area upstream in a sheet conveying direction is lower than an electric voltage value for an electric supplying means arranged at a secondary area downstream of the primary area in a sheet conveying direction.
According to the embodiment described afterwards, when an electric supplying means supplies electric voltage to an electrode, a low voltage is supplied first, and then a higher voltage is supplied; accordingly, compared to a case where a high voltage is suddenly supplied, the shock when making contact could be reduced and a creation of noise and the deterioration of a electric supplying brush could be restrained.
Further, this invention provides a sheet conveying device for attracting (absorbing) a sheet by electric power and conveying the sheet, the sheet conveying device comprising: a belt arranged with an electrode; and a plurality of electric supplying means being aligned in a sheet conveying direction for supplying electric voltage to the electrode, wherein an electric supply control means is provided for changing the electric voltage value of the plurality of electric supplying means.
Since an electric supply control means for changing the electric voltage value of an electric supplying means is provided, attraction strength most suitable for conveying a sheet could be generated by changing the electric voltage value of an electric supplying means in accordance with environmental conditions such as humidity or conditions such as the characteristic of a sheet.
Another structure of this invention for achieving the aforementioned object is a sheet conveying device supplying electric voltage to a non-end belt member while rotating the belt member, and conveying a sheet by attracting the sheet to a surface of the belt member, the sheet conveying device comprising: an electric supplying means being capable of supplying electric voltage to a belt member having a targeted electric supply portion, and having a plurality of electric supplying members aligned in a conveying direction; and a control means for controlling the electric voltage value of electric voltage supplied from the plurality of electric supplying members of the electric supplying means to the targeted electric supply portion of the belt member, wherein an electric supplying member of the electric supplying means being most upstream in a conveying direction gradually raises the electric voltage from a secondary electric voltage value being smaller than a primary electric voltage value for allowing attraction of a sheet upon the belt member after making contact to a targeted electric supply portion of the belt member, and raises the electric voltage to the primary electric voltage value until separated from the targeted electric supply portion.
With this invention, the electric supplying means having plural electric supplying members aligned in the conveying direction serves to reduce shock during contact compared to a case of suddenly applying high voltage so as to heighten the endurance for an electric supplying member, in which an electric supplying member at a non-recording area positioned upstream of a recording area gradually raises electric voltage from a secondary electric voltage value being smaller than that of the primary electric voltage value for allowing a sheet to be attracted (absorbed) upon a belt member after making contact with a targeted electric supply portion of the belt member, and the electric voltage is raised to the primary electric voltage value until being separated from the targeted electric supply portion. Accordingly, the noise caused by the conveyor belt could be exceedingly reduced to allow the device to operate steadily.
As for another structure of this invention, a sheet conveying device supplying electric voltage to a non-end belt member while rotating the belt member, and conveying a sheet by attracting the sheet to a surface of the belt member, the sheet conveying device comprising: an electric supplying means being capable of supplying electric voltage to a belt member having a targeted electric supply portion, and having a plurality of electric supplying members aligned in a conveying direction; and a control means for controlling the electric voltage value of electric voltage supplied from the plurality of electric supplying members of the electric supplying means to the targeted electric supply portion of the bolt member, wherein an electric supplying member of the electric supplying means being most downstream in a conveying direction gradually lowers the electric voltage from a primary electric voltage value for allowing attraction (absorption) of a sheet upon the belt member after making contact to a targeted electric supply portion of the belt member, and lowers the electric voltage to a secondary electric voltage value being smaller than the primary electric voltage value until separated from the targeted electric supply portion.
With this invention, the electric supplying means serves to allow reduction of shock during removal of electricity compared to the shock of suddenly short-circuiting and results to heighten the endurance for an electric supplying member, in which an electric supplying member at a non-recording area positioned downstream of a recording area gradually lowers electric voltage from a primary electric voltage value for allowing a recording medium to be attracted upon a belt member after making contact with a targeted electric supply portion of the belt member, and the electric voltage is lowered to the secondary electric voltage value being smaller than the primary electric voltage value until being separated from the targeted electric supply portion. Accordingly, the noise caused by the conveyor belt could be exceedingly reduced to allow the device to operate steadily.